A Microfluidic Device with a Diffusion Barrier

Abstract

The invention provides a microfluidic device for macromolecule amplification by sequential addition of liquid reagents. The device of the invention comprises a chip forming a plurality of reaction chambers each extending between an inlet and an outlet, each inlet being in fluid communication with a common junction via micro channels. To enable amplification of DNA, e.g. by MDA, the device comprises a diffusion barrier at each inlet configured to increase the pressure threshold for a reagent to cross the resistor. The invention further provides a method of mixing liquid reagents by use of the device where single DNA molecules are allowed to cross the diffusion barrier individually.

1 . A microfluidic device for macromolecule amplification by sequential addition of liquid reagents, the device comprising, a chip forming a plurality of reaction chambers each extending between an inlet and an outlet, each inlet being in fluid communication with a common junction via micro channels, characterised in that the device comprises a diffusion barrier at each inlet configured to increase the pressure threshold for a reagent to cross the diffusion barrier. 
     
     
         2 . The device according to  claim 1 , where each diffusion barrier is configured to prevent diffusion of macromolecules including genomic DNA and enzymes in or out of the reaction chambers. 
     
     
         3 . The device according to  claim 1 , where the diffusion barrier has a largest dimension in the range of 10-500 nm. 
     
     
         4 . The device according to  claim 1 , where the chamber, micro channels, and the diffusion barrier are constituted by recesses in a surface of the chip, the recesses constituting the diffusion barrier having a lower depth than the recesses constituting the micro channels and chambers. 
     
     
         5 . The device according to  claim 4 , where the recesses are covered by a cover layer bonded to the surface. 
     
     
         6 . The device according to  claim 1 , comprising a plurality of reagent delivery ports where each port has an associated delivery conduit extending from the delivery port to the common junction. 
     
     
         7 . The device according to  claim 6 , where the reagent delivery ports are all on the same side of the chip. 
     
     
         8 . The device according to  claim 1 , further comprising a pressure control structure configured to apply control pressures at least at each outlet and at the common junction. 
     
     
         9 . The device according to  claim 8 , where the pressure control structure is configured to control pressure individually at each delivery port. 
     
     
         10 . The device according to  claim 1 , where the chambers are located in a circular layout about the common junction. 
     
     
         11 . The device according to  claim 1 , wherein the chip forms the reaction chambers, the inlets, the outlets, the common junction, and optionally the ports and the delivery conduits in one piece. 
     
     
         12 . The device according to  claim 1 , where at least the diffusion barrier is made from a material selected from the group consisting of polypropylene, polyethylene, and amorphous polymer cyclic olefin copolymer materials. 
     
     
         13 . The device according to  claim 1 , where the chip is moulded in a material selected from the group consisting of polypropylene, polyethylene, and amorphous polymer cyclic olefin copolymer materials. 
     
     
         14 . The device according to  claim 1 , where each chamber has at least one transparent or translucent wall section. 
     
     
         15 . A method of mixing liquid reagents by use of a device according to  claim 1 , the method comprising providing a flow of the liquid reagents through the reaction chamber, where the flow speed is adjusted by use of pressure control such that single DNA molecules are allowed to cross the diffusion barrier individually. 
     
     
         16 . The method according to  claim 15 , comprising mixing a hydrogel polymer into the liquid reagent and use local heating to thereby create a gel to reduced liquid flow through the diffusion barrier.